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 Post subject: Beta 38 - vented loop
PostPosted: 08 Apr 2019 07:25 
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Joined: 04 Aug 2013 13:33
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Beta installation manual calls for almost 20" of height above the static waterline on the vented loop. There is only 14" to the underside of the cockpit (including 1 1/4" sound-proofing).

Has anyone installed a Beta 38 (with the high rise exhaust) without a vented loop? Where is your vented loop installed? The Westerbeke had one just above the Vernalift muffler just under the cockpit. This height is just enough for the height requirement in my old Yanmar installation manual. Is Beta just more conservative? I'm thinking of installing the loop at 20" in the cockpit locker bulkhead and running the vent to one of the bilge hose exits.

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Dave Lorick
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 Post subject: Re: Beta 38 - vented loop
PostPosted: 08 Apr 2019 19:18 
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Joined: 14 Jul 2012 20:36
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I took my Beta 35 vented loop to the bottom of the cockpit floor, with drain hose to bilge. Been in some salty following seas, like +10ft, blowing 30 across the deck for two days. No problems so far. I also have high rise manifold and Vernalift muffler. The new exhaust hose, I ran it as high as I could get in the port side cockpit coming, mounting to the bulkhead. I had heard of one Beta back flooded.

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 Post subject: Re: Beta 38 - vented loop
PostPosted: 28 Jul 2019 08:52 
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Joined: 04 Aug 2013 13:33
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When I installed the Beta 38, I ordered a new Vernalift / Centek wet muffler like the old one (since everything else is now new). After reading more about hydro-locking from poorly designed wet exhaust systems, I sent it back for the next size larger (from approx. 1 gal capacity rating to 1.25). The larger wet muffler would be able to accommodate the water volume in the vented loop and exhaust hoses if they were full and all drained into the muffer.

To get the altitude Beta specifies for the vented loop, I mounted it high on the inboard/forward corner of the cockpit locker. This makes it easier to remove the screw-on cap from the Groco bronze loop for inspection and cleaning. In case the check valve fails, there is a hose that would direct any flow overboard as well as provide air to break any siphon.

Positioning the loop off centerline lowers it when heeled (on port tack), but the rail would be under water before this position on the loop would be lower than the centerline.

Vernalift is now owned by Centek. The model shown is 1500027. The curve cut out of the new water heater base was to make room for the new water muffler. The tight space between the drive shaft and port stem required moving the wet muffler aft requiring a cutout in the base and repositioning the water heater further aft.

Also pictured is the exhaust expansion loop mounted up inside the port cockpit coaming. The original exhaust hose had a slight low spot from this point to the transom. I notched out a bit of the lazzarette to make a smooth run aft. So far, so good - everything appears to be running great.


Attachments:
File comment: Beta-supplied expansion chamber
Beta expansion loop 20190623 .jpg
Beta expansion loop 20190623 .jpg [ 3.74 MB | Viewed 0 times ]
File comment: Wet muffler - curved cutout in water heater base to accommodate
Vernalift 20190623 .jpg
Vernalift 20190623 .jpg [ 3.34 MB | Viewed 0 times ]
Vented Loop to engine 20190623.jpg
Vented Loop to engine 20190623.jpg [ 3.7 MB | Viewed 0 times ]
Vented Loop - 20190623.jpg
Vented Loop - 20190623.jpg [ 1.93 MB | Viewed 0 times ]

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Dave Lorick
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 Post subject: Re: Beta 38 - vented loop
PostPosted: 29 Jul 2019 07:21 
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Joined: 29 Dec 2006 09:38
Posts: 537
puffcard wrote:
I took my Beta 35 vented loop to the bottom of the cockpit floor, with drain hose to bilge. Been in some salty following seas, like +10ft, blowing 30 across the deck for two days. No problems so far. I also have high rise manifold and Vernalift muffler. The new exhaust hose, I ran it as high as I could get in the port side cockpit coming, mounting to the bulkhead. I had heard of one Beta back flooded.

FWIW: the vented loop is not to protect your engine from following seas. Installation of the exhaust line high into the coaming on the way to the stern fitting is supposed to take care of following seas. If you are doing the installation yourself (or under the “professionals” I see at some of the boat yards) you need to ensure that you get that exhaust hose high in the coaming—very high— as Tartan did with with the Westerbeast—that is the only thing protecting you from following seas filling your exhaust system if the engine is not running. The vent discussed here is to break a potential siphon because the raw water engine intake and output could be under water at that same time and a siphon could be created that would fill the engine from the exhaust loop backward into the cylinders. The actual engine location in these boats is mostly below the waterline outside. Seems like the Beta location is a bit of overkill—but I have a Yanmar installation and it is possible that the Beta “high rise” exhaust actually raises the water level high enough to threaten your engine. I do not like salt water that close to the innards of my engine if that is the case. Yikes. If someone has the diagram of the recommended Beta installation, that would be interesting to see their design and rationale. As I have said before, the biggest problems I have seen with small marine diesel engines is the design and maintenance of the raw water systems and coolant process—the engine blocks and running gear are more or less common among all of the small diesels. But this is not a small matter when it comes to longevity in a salt water environment IMHO. I always thought the W50 was a fine old diesel, it was just the Westerbeke cobbled a poorly designed, maintenance-intense raw water and cooling system on a decent block and made a maintenance and reliability nightmare out of it. I fear this could be happening again with Beta. I realize there are a lot of Beta supporters out there. And I agree that Yanmar support for DIY folks from Mack Boring sucks which is costing Yanmar the small end of their business with a superiorly engineered product. Your turn.
Ray


 
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 Post subject: Re: Beta 38 - vented loop
PostPosted: 29 Jul 2019 18:19 
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Joined: 04 Aug 2013 13:33
Posts: 228
Your reason for the high exhaust loop and the anti-siphon match all I have heard or read on the subject.

The difference of the height of the anti-siphon is 20" specified by Beta and almost 14" by Yanmar (at least for my old 2GM20 - 13.78").

A common failure on the vented loop is the duck-bill style check valve getting crusted with salt. It is difficult to check when mounted high close to the underside of the cockpit the way mine was originally. The new vent has a large screw top just inside the locker that should make it much easier to check (so it'll be more likely I look in their once in a while).

The red expansion chamber at the top of the exhaust hose is something I never heard of before. Beta sells it as an option to help in a following sea as you described. Hope I'm lucky enough to never give it a good test...!

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Dave Lorick
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 Post subject: Re: Beta 38 - vented loop
PostPosted: 30 Jul 2019 15:28 
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Joined: 04 Aug 2013 13:33
Posts: 228
Ray,
here are attached are 5 pages from the installation manual showing wet exhaust system. The entire PDF is here:
https://www.betamarinenc.com/wp-content ... _Guide.pdf

The high loop means the water level in the system must rise higher before reaching the exhaust outlet to enter the engine. The water inlet is on the downhill portion of the exhaust loop. The water enters a jacket around the exhaust pipe (for cooling). The water must reach the end of the steel pipe at the low point of the loop where the hose attaches before reaching the exhaust outlet.

I know what you mean about the Yanmar's apparent disinterest in small marine engine business. When looking at Beta, I also filled out a repower inquiry on Mastry Engine's website (in St Petersburg, FL) - twice.

They are or were the Southeast distributor for Yanmar - where I bought a 2GM20 many years ago. I never got a reply. On the other hand, Beta Marine in NC was experienced with Tartan 37 repowers and helpful before and after the sale.


Attachments:
File comment: Just 5 pages on wet exhaust system
Engine_Installation_Guide.pdf [1.26 MB]
Downloaded 3 times

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